Ham radio enthusiasts, people looking to borrow their neighbors’ WiFi, and those interested in decoding signals from things like weather satellites will often grab an old satellite TV antenna and repurpose it. Customers have been leaving these services for years, so they’re pretty widely available. But for handheld operation, these metal dishes can get quite cumbersome. A 3D-printed satellite dish like this one is lightweight and small enough to be held, enabling some interesting satellite tracking activities with just a few other parts needed.

Although we see his projects often, [saveitforparts] did not design this antenna, instead downloading the design from [t0nito] on Thingiverse. [saveitforparts] does know his way around a satellite antenna, though, so he is exactly the kind of person who would put something like this through its paces and use it for his own needs. There were a few hiccups with the print, but with all the 3D printed parts completed, the metal mesh added to the dish, and a correctly polarized helical antenna formed into the print to receive the signals, it was ready to point at the sky.

The results for the day of testing were incredibly promising. Compared to a second satellite antenna with an automatic tracker, the handheld 3D-printed version captured nearly all of the information sent from the satellite in orbit. [saveitforparts] plans to build a tracker for this small dish to improve it even further. He’s been able to find some satellite trackers from junked hardware in some unusual places as well. Antennas seem to be a ripe area for 3D printing.

The ESP32 is s remarkably powerful microcontroller, where its dual-core processor and relatively high clock speed can do some impressive work. But getting this microcontroller designed for embedded systems to do tasks that would generally be given to a much more powerful PC-type computer takes a little bit more willpower. Inspired by his dog, [Folkert] decided to program an ESP32 to play chess, a famously challenging task for computer scientists in the past. He calls this ESP32 chess system Dog.

One of the other major limitations of this platform for a task like this is memory. The ESP32 [Folkert] is using only has 320 kB of RAM, so things like the transposition table have to fit in even less space than that. With modern desktop computers often having 32 or 64 GB, this is a fairly significant challenge, especially for a memory-intensive task like a chess engine. But with the engine running on the microcontroller it’s ready to play, either in text mode or with something that can use the Universal Chess Interface (UCI). A set of LEDs on the board lets the user know what’s going on while gameplay is taking place.

The UCI also enables Dog to play online at lichess.org, and [Folkert] has included a link on the project page where others can play with his microcontroller chess system this way through the Internet. It has a pretty respectable Elo rating at around 2100 as well, so don’t think that just because it’s a small platform that the wins will come easy. If you’d prefer your chess engines to run on retro hardware, take a look at this build, which also uses an ESP32 but puts it to work by running old Commodore chess equipment from the 80s. Of course, you can play chess on even less hardware. It has been done.

There are certain tasks that humans perform every day that are notoriously difficult for computers to figure out. Identifying objects in pictures, for example, was something that seems fairly straightforward but was only done by computers with any semblance of accuracy in the last few years. Even then, it can’t be done without huge amounts of computing resources. Similarly, driving a car is a surprisingly complex task that even companies promising full self-driving vehicles haven’t been able to deliver despite working on the problem for over a decade now. [Austin] demonstrates this difficulty in his latest project, which adds self-driving capabilities to a small go-kart.

[Austin] had been working on this project at the local park but grew tired of packing up all his gear when he wanted to work on his machine-learning algorithms. So he took all the self-driving equipment off of the first kart and incorporated it into a smaller kart with a very small turning radius so he could develop it in his shop.

He laid down some tape on the floor to create the track and then set up the vehicle to learn how to drive by watching and gathering data. The model is trained with a convolutional neural network and this data. The only inputs that the model gets are images from cameras at the front of the kart. At first, it could only change the steering angle, with [Austin] controlling the throttle to prevent crashes. Eventually, he gave it control of the throttle as well, which behaves well except at the fastest speeds.

There were plenty of challenges along the way, especially when compared to the models trained at the park; [Austin] correctly theorized that the cause of the hardship in the park was a lack of contrast at the boundary between the track and any out-of-bounds areas. With a few tweaks to the track, as well as adding some wide-angle lenses to his cameras, he was able to get a model that works fairly well. Getting started on a project like this doesn’t have as high of a barrier to entry as one might imagine, either. Take a look at this comprehensive open-source Python library for self-driving projects. If you want to start smaller, perhaps don’t start with a self-driving kart.

Although a lot of tools have been digitized and consolidated into our smartphones, from cameras, music players, calendars, alarm clocks, flashlights, and of course phones, perhaps none are as useful as the GPS and navigational capabilities. The major weakness here, though, is that this is a single point of failure. If there’s no cell service, if the battery dies, or you find yourself flying a bomber during World War II then you’re going to need another way to navigate, possibly using something like this Astro Compass.

The compass, as its name implies, also doesn’t rely on using the Earth’s magnetic field since that would have been difficult or impossible inside of an airplane. Instead, it can use various celestial bodies to get a heading. But it’s not quite as simple as pointing it at a star and heading off into the wild blue yonder. First you’ll need to know the current time and date and look those up in a companion chart. The chart lists the global hour angle and the declination for a number of celestial bodies which can be put into the compass. From there the latitude is set and the local hour angle is calculated and set, and then the compass is rotated until the object is sighted. After all of that effort, a compass heading will be shown.

For all its complexity, a tool like this can be indispensable in situations where modern technology fails. While it does rely on precise tabulated astrometric data to be on hand, as long as that’s available it’s almost failsafe, especially compared to a modern smartphone. Of course, you’ll also need a fairly accurate way of timekeeping which can be difficult in some situations.

Most small-scale, residential rainwater harvesting systems we’ve seen rely on using an existing roof and downspout to collect water that would otherwise be diverted out into the environment. These are accessible for most homeowners since almost all of the infrastructure needed for it is already in place. [SuburbanBiology] already built one of these systems to take care of his potable water, though, and despite its 30,000 gallon capacity it’s not even close to big enough to also water his garden. But with some clever grading around his yard and a special rainwater system that harvests rain from the street instead of his roof, he’s capable of maintaining a lush food forest despite living through a drought in Texas.

For this build there are actually two systems demonstrated, one which is gravity-fed from the road and relies on one’s entire property sloping away from the street, and a slightly more complex one that’s more independent of elevation. Both start with cutting through a section of sidewalk to pass a 4″ PVC pipe through to the street where the stormwater runoff can be collected. The gravity-fed system simply diverts this into a series of trenches around the property while the second system uses a custom sump pump to deliver the water to the landscaping.

For a system like this a holding tank is not necessary; [SuburbanBiology] is relying on the soil on his property itself to hold onto the rainwater. Healthy, living soil can hold a tremendous amount of water for a very long time, slowly releasing it to plants when they need it. And, at least where he lives, a system like this is actually helpful for the surrounding environment as a whole since otherwise all of the stormwater runoff has to be diverted out of the city or cause a flood, and it doesn’t end up back in an aquifer. If you’re more curious about a potable water system instead, take a look at [SuburbanBiology]’s previous system.

We all carry touch screen computers around in our pockets these days, but before the smartphone revolution, there was the personal digital assistant (PDA). While it wasn’t a commercial success, one of the first devices in this category was the Apple Newton. Today they’re sought after by collectors, although most of the ones surviving to this day need a bit of rework to the battery pack. Luckily, as [Robert’s Retro] shows, it’s possible to rebuild the pack with modern cells.

By modern standards, the most surprising thing about these battery packs is both that they’re removable and that they’re a standard size, matching that of AA batteries. The Newton battery pack uses four cells, so replacing them with modern rechargeable AA batteries should be pretty straightforward, provided they can be accessed. This isn’t as easy, though. In true Apple fashion the case is glued shut, and prying it apart can damage it badly enough so it won’t fit back in the tablet after repair is complete. The current solution is to cut a hatch into the top instead and then slowly work on replacing the cells while being careful to preserve the electronics inside.

[Robert’s Retro] also demonstrates how to spot weld these new AA batteries together to prepare them for their new home in the Newton case. With the two rows fastened together with nickel strips they can be quickly attached to the existing electrical leads in the battery pack, and from there it’s just a matter of snapping the batteries into the case and sliding it back into the tablet. If you’re looking for something a bit more modern, though, we’d recommend this Apple tablet-laptop combo, but it’s not particularly easy on the wallet.

For better or worse, a lot of human technology is confined to fewer dimensions than the three we can theoretically move about in. Cars and trains only travel two dimensionally with limited exceptions, maps and books generally don’t take advantage of a third dimension, and most computer displays and even the chips that make them work are largely two-dimensional in nature. Most styles of cooking can only apply heat in a single dimension as well, but [Dane Kouttron] wanted to make sure the meat his cookouts took advantage of a truly three-dimensional cooking style by adding a gyroscopic mechanism to the spit.

The first thing that needed to be built were a series of concentric rings for each of the three axes of rotation. Metal tubes were shaped with a pipe bender and then welded into their final forms, with an annealing step to flatten the loops. From there, the rings are attached to each other with a series of offset bearings. The outer tube is mounted above the fire and a single motor spins this tube. Since no piece of meat is perfectly symmetrical (and could be offset on the interior ring a bit even if it were) enough chaos is introduced to the system that the meat is free to rotate in any direction, change direction at any time, and overall get cooked in a more uniform way than a traditional single-dimensional rotating spit.

As a proof of concept [Dane] hosted a cookout and made “gyro” sandwiches (even though the machine may technically be more akin to a gimbal), complete with small Greek flag decorative garnishes. It seems to have been a tremendous success as well. There are a few other novel ways we’ve seen of cooking food over the years, including projects that cook with plasma and much more widely available methods that cook food efficiently using magnets, of a sort.

Although there might have been other music produced or recorded in the 1980s, we may never know of its existence due to the cacophony of all of the various keytars, drum machines, and other synthesized music playing nonstop throughout the decade. There was perhaps no more responsible synthesizer than the Yamaha DX7 either; it nearly single-handedly ushered in the synth pop era. There had been other ways of producing similar sounds before but none were as unique as this keyboard, and for ways beyond just its sound as [Kevin] describes in this write-up.

Part of the reason the DX7 was so revolutionary was that it was among the first accessible synthesizers that was fully digital, meaning could play more than one note at a time since expensive analog circuitry didn’t need to be replicated for multiple keys. But it also generated its tones by using frequency modulation of sine waves in a way that allowed many signals to be combined to form different sounds. While most popular musicians of the 80s used one of the preset sounds of the synthesizer, it could produce an incredible range of diverse sounds if the musician was willing to dig a bit into the programming of this unique instrument.

There were of course other reasons this synthesizer took off. It was incredibly robust, allowing a musician to reliably carry it from show to show without much worry, and it also stood on the shoulders of giants since musicians had been experimenting with various other types of synthesizers for the previous few decades. And perhaps it was at the right place and time for the culture as well. For a look at the goings on inside the chip that powered the device, [Ken Shirriff] did a deep dive into one a few years ago.

The extended filesystem, otherwise known as ext, has been a fundamental part of Linux since before the 1.0 release in 1994. Currently the filesystem is on its fourth major revision, in use since its release in 2008 thanks to its stability, reliability, and backwards compatibility with the other ext filesystem versions. But with that much history there are bound to be a few issues cropping up here and there. [Will] recently found an exploit with this filesystem that can cause a Linux kernel to immediately panic when a manipulated USB drive is inserted into a computer.

[Will] discovered this quirk when investigating the intricacies of the filesystem for problems and other vulnerabilities. A tool called tune2fs, used for administering and modifying ext filesystems, includes the ability to pass certain commands to the Linux kernel when certain situations arise with the filesystem itself, including that the kernel should panic. One situation is that the ext filesystem itself becomes corrupted, which can then cause the kernel panic. Armed with this knowledge, a USB drive can be purposefully given a corrupted ext filesystem which, when plugged into a Linux machine, can cause the computer to shut down.

The post linked above goes into some discussion about how this exploit could be used maliciously to gain access to a Linux system, including rebooting computers where no access to a power button is otherwise enabled or making other changes to the system before needing a reboot to apply the changes. In general, though, it’s good to assume an attacker could take any route to gain access to a machine. This exploit from a few years ago, for example, allowed another Linux tool to be used to gain root access.

Thanks to [Timothy] for the tip!

Anyone who has operated a 3D printer before, especially those new to using these specialized tools, has likely had problems with the print bed. The bed might not always be the correct temperature leading to problems with adhesion of the print, it could be uncalibrated or dirty or cause any number of other issues that ultimately lead to a failed print. Most of us work these problems out through trial and error and eventually get settled in, but this novel 3D printer instead removes the bed itself and prints on whatever surface happens to be nearby.

The printer is the product of [Daniel Campos Zamora] at the University of Washington and is called MobiPrint. It uses a fairly standard, commercially available 3D printer head but attaches it to the base of a modified robotic vacuum cleaner. The vacuum cleaner is modified with open-source software that allows it to map its environment without the need for the manufacturer’s cloud services, which in turn lets the 3D printer print on whichever surface the robot finds in its travels. The goal isn’t necessarily to eliminate printer bed problems; a robot with this capability could have many more applications in the realm of accessibility or even, in the future, printing while on the move.

There were a few surprising discoveries along the way which were mentioned in an IEEE Spectrum article, as [Campos Zamora] found while testing various household surfaces that carpet is surprisingly good at adhering to these prints and almost can’t be unstuck from the prints made on it. There are a few other 3D printers out there that we’ve seen that are incredibly mobile, but none that allow interacting with their environment in quite this way.

It’s one of the great tragedies of our technological era. Smartphones that feature an incredible amount of computational power compared to computers the past, are largely locked down by carriers or manufacturers, dooming them to performing trivial tasks far below their true capabilities.

But there is hope. In part one of this build, a OnePlus 6T is stripped of its Android operating system in favor of postmarketOS, a Linux distribution based on Alpine designed for a number of Android phones and tablets as well as some Linux-only handhelds. The guide also demonstrates how to remove the battery and use a modified USB-C cable to essentially trick the battery management system into powering up the phone anyway. The second part of the project dives into the software side, getting the Linux system up and running before installing Docker and whichever Docker containers the user needs.

There are a few downsides to running a server from a smartphone. Although there’s plenty of processing power available for a wide range of applications, most phones won’t have Ethernet support out-of-the-box which forces the use of WiFi. There’s also limited storage options available, so a large NAS system may be out of reach. But for something like a home automation system or a music streaming server this could put plenty of older devices to work again. And if you don’t want to hunt for an Android phone that isn’t completely hobbled out-of-the box you might want to try a phone that’s Linux-based from the get-go instead.

Thanks to [JohnU] for the tip!

When thinking of retrocomputing, many of us will imagine machines such as the Commodore 64 or Apple II. These computers were very popular and have plenty of parts and documentation available. Fewer will go back to the Intel 8008 or even 4004 era which were the first integrated circuit chips commercially available. But before even those transistor-based computers is a retrocomputing era rarely touched on: the era of programmable vacuum tube machines. [Mike] has gone back to the 1950s with this computer which uses vacuum tubes instead of transistors.

The computer has an eight-bit architecture and features most of the components of any modern transistor-based computer of similar computational ability. Memory, I/O, an arithmetic logic unit including a carry bit that allows it to do 16-bit arithmetic, are all implemented using 6N3P dual triode tubes that date to the 50s and 60s and would have been used in similar computers like the IBM 700. All of this drives a flight simulator program or a Fibonacci number generator, demonstrating its general purpose computing capabilities.

Of course, tubes were generally phased out in favor of transistors largely due to their power and space requirements; [Mike] needs a stepladder to maintain this computer as well as around ten minutes each time he starts it up to allow the tubes to warm up, with each module needing over three amps of current each. It’s a hugely impressive build and we’d recommend checking out the video linked below to get more details on its operation. If you’re looking for something a little more accessible to get into the world of vacuum tubes, this single-board tube computer fits the bill.

For the cautious, a good piece of advice is to always wait to buy a new product until after the first model year, whether its cars or consumer electronics or any other major purchase. This gives the manufacturer a year to iron out the kinks and get everything ship shape the second time around. But not everyone is willing to wait on new tech. [Berto] has been interested in lithium capacitors, a fairly new type of super capacitor, and being unwilling to wait on support circuitry schematics to magically show up on the Internet he set about making his own.

The circuit he’s building here is a solar charger for the super capacitor. Being a fairly small device there’s not a lot of current, voltage, or energy, but these are different enough from other types of energy storage devices that it was worth taking a close look and designing something custom. An HT7533 is used for voltage regulation with a Schottky diode preventing return current to the solar cell, and a DW01 circuit is used to make sure that the capacitor doesn’t overcharge.

While the DW01 is made specifically for lithium ion batteries, [Berto] found that it was fairly suitable for this new type of capacitor as well. The capacitor itself is suited for many low-power, embedded applications where a battery might add complexity. Capacitors like this can charge much more rapidly and behave generally more linearly than their chemical cousins, and they aren’t limited to small applications either. For example, this RC plane was converted to run with super capacitors.

It might come as a surprise to some that IEEE, the Institute for Electrical and Electronics Engineers, does more than send out mailers asking people to renew their memberships. In fact, they also maintain various electrical standards across a wide range of disciplines, but perhaps the one most of us interact with the most is the 802.11 standard which outlines WiFi. There have been many revisions over the years to improve throughput but the 802.11ah standard actually looks at decreasing throughput in favor of extremely increased range. Just how far you can communicate using this standard seems to depend on how many drones you have.

802.11ah, otherwise known as Wi-Fi HaLow, operates in the sub-gigahertz range which is part of why it has the capability of operating over longer distances. But [Aaron] is extending that distance even further by adding a pair of T-Halow devices, one in client mode and the other in AP (access point) mode, on a drone. The signal then hops from one laptop to a drone, then out to another drone with a similar setup, and then finally down to a second laptop. In theory this “Dragon Bridge” could allow devices to communicate as far as the drone bridge will allow, and indeed [Aaron] has plans for future revisions to include more powerful hardware which will allow even greater distances to be reached.

While there were a few bugs to work out initially, eventually he was able to get almost two kilometers of distance across six devices and two drones. Something like this might be useful for a distributed network of IoT devices that are just outside the range of a normal access point. The Dragon Bridge borrowed its name from DragonOS, a Linux distribution built by [Aaron] with a wide assortment of software-defined radio tools available out of the box. He’s even put in on the Steam Deck to test out long-distance WiFi.

Although humanity was hoping for a more optimistic robotic future in the post-war era, with media reflecting that sentiment like The Jetsons or Lost in Space, we seem to have shifted our collective consciousness (for good reasons) to a more Black Mirror/Terminator future as real-world companies like Boston Dynamics are actually building these styles of machines instead of helpful Rosies. But this future isn’t guaranteed, and a PhD researcher is hoping to claim back a more hopeful outlook with a robot called Blossom which is specifically built to investigate how humans interact with robots.

For a platform this robot is not too complex, consisting of an accessible frame that can be laser-cut from wood with only a few moving parts controlled by servos. The robot is not too large, either, and can be set on a desk to be used as a telepresence robot. But Blossom’s creator [Michael] wanted this to help understand how humans interact with robots so the latest version is outfitted not only with a large language model with text-to-speech capabilities, but also with a compelling backstory, lore, and a voice derived from Animal Crossing that’s neither human nor recognizable synthetic robot, all in an effort to make the device more approachable.

To that end, [Michael] set the robot up at a Maker Faire to see what sorts of interactions Blossom would have with passers by, and while most were interested in the web-based control system for the robot a few others came by and had conversations with it. It’s certainly an interesting project and reminds us a bit of this other piece of research from MIT that looked at how humans and robots can work productively alongside one another.

By default, bash is the most popular command language simply because it’s included in most *nix operating systems. Additionally, people don’t tend to spend a lot of time thinking about whatever their computer uses for scripting as they might for other pieces of software like a word processor or browser. If you are so inclined to take a closer look at this tool that’s often taken for granted, there are a number of alternatives to bash and [monzool] wanted to investigate them closely.

Unlike other similar documentation that [monzool] has come across where the writers didn’t actually use the scripting languages being investigated, [monzool] is planning to use each of these and accomplish specific objectives. This will allow them to get a feel for the languages and whether or not they are acceptable alternatives for bash. Moving through directories, passing commands back and forth, manipulating strings, searching for files, and manipulating the terminal display settings are all included in this task list. A few languages are tossed out before initial testing even begins for not meeting certain specific requirements. One example is not being particularly useful in [monzool]’s preferred embedded environments, but even so there are enough bash alternatives to test out ten separate languages.

Unfortunately, at the end of the day none of the ten selected would make a true replacement for bash, at least for [monzool]’s use case, but there were a few standouts nonetheless. Nutshell was interesting for being a more modern, advanced system and [monzool] found Janet to be a fun and interesting project but had limitations with cross-compiling. All in all though this seemed to be an enjoyable experience that we’d recommend if you actually want to get into the weeds on what scripting languages are actually capable of. Another interesting one we featured a while back attempts to perform as a shell and a programming language simultaneously.

For a lot of electrical and mechanical machines, there are nominal and peak ratings for energy output or input. If you’re in marketing or advertising, you’ll typically look at the peak rating and move on with your day. But engineers need to know that most things can only operate long term at a fraction of this peak rating, whether it’s a power supply in a computer, a controller on an ebike, or the converter on a wind turbine. But this electric motor system has a unique cooling setup allowing it to function at nearly full peak rating for an unlimited amount of time.

The motor, called the Super Continuous Torque motor built by German automotive manufacturer Mahle is capable of 92% of its peak output power thanks to a unique oil cooling system which is able to remove heat and a rapid rate. Heat is the major limiter for machines like this; typically when operating at a peak rating a motor would need to reduce power output to cool down so that major components don’t start melting or otherwise failing. Given that the largest of these motors have output power ratings of around 700 horsepower, that’s quite an impressive benchmark.

The motor is meant for use in passenger vehicles but also tractor-trailer style trucks, where a motor able to operate at its peak rating would mean a smaller size motor or less weight or both, making them easier to fit into the space available as well as being more economically viable. Mahle is reporting that these motors are ready for production so we should be seeing them help ease the transportation industry into electrification. If you’re more concerned about range than output power, though, there’s a solution there as well so you don’t have to be stuck behind the times with fossil fuels forever.

Thanks to [john] for the tip!